Finding the Sub String in C.

#include<stdio.h>

int main()

{

    char str[30], sea[30];

    int c1 = 0, c2 = 0, i, j, f;

    printf("a
Please Enter a string:");

    gets(str);

    printf("
Please Enter search word:");

    gets(sea);

    while (str[c1] != '') ///counting the length

        c1++;

    while (sea[c2] != '')  ///counting the length

        c2++;

     

    ///Checking for sub string  

    for (i = 0; i <= c1 - c2; i++)

    {

        for (j = i; j < i + c2; j++)

        {

            f = 1;

            if (str[j] != sea[j - i])

            {

                f = 0;

                break;

            }

        }

        if (f == 1)

            break;

    }

   

   

    if (f == 1)

        printf("a
Yes
");

    else

        printf("a
No
");

    return 0;

}